1. Field of the Invention
Embodiments of the present invention generally relate to monitoring the rotation of a member in a reciprocating rod lift system.
2. Description of the Related Art
The production of oil with a sucker-rod pump is common practice in the oil and gas industry. An oil well generally comprises a casing, a string of smaller steel pipe inside the casing and generally known as the tubing, a pump at the bottom of the well, and a string of steel rods, commonly referred to as sucker rods, within the tubing and extending down into the pump for operating the pump. Various devices as are well known in the art are provided at the top of the well for reciprocating the sucker rod to operate the pump.
The crude oil generally contains paraffin and other substances which tend to congeal and precipitate out of the oil and deposit upon the walls of the tubing during the passage of the oil through the tubing. Such deposits are quite objectionable and tend to restrict the flow of oil through the tubing. Moreover, operating the pump with an excessive amount of the deposits may lead to severe rod and tubing wear. Various means and methods have been proposed for preventing the formation of such deposits and for removing deposits so formed. Such means and methods generally include the use of chemicals, electrical heating and various mechanical scraping devices. In general, such means and methods may be expensive and have other objectionable features.
A common mode of preventing the formation of deposits on the tubing and removing such deposits as they are formed generally include attaching paraffin scrapers to the sucker rod. Such sucker rods may remove the deposits from the oil well tubing as it is formed so that it is flushed out of the well with the oil passing therethrough. In many cases, the means for reciprocating the sucker rods include devices, such as a rod rotator, for rotating the rods through a predetermined angle during each stroke of the sucker rods. The rod rotator may be installed on the wellhead and connected to a walking beam. With each stroke of the pumping unit, the rotator may rotate the rods a fraction of one revolution. As the rods are rotated, paraffin may be scraped off the walls of the tubing in an effort to distribute wear.